SEOUL (Reuters) -- North Korea has released two jailed American journalists after a visit from former U.S. President Bill Clinton in the highest-level U.S. contact with North Korea since Clinton was president nearly a decade ago.

North Korea's KCNA news agency said North Korean leader Kim Jong Il had issued a special pardon to the two journalists, Euna Lee and Laura Ling of U.S. media outlet Current TV, which was co-founded by Clinton's vice president, Al Gore.

Clinton was the highest-level American to visit North Korea since his secretary of state, Madeleine Albright, went there in 2000.

He was greeted warmly on his arrival and had what North Korea's KCNA news agency described as an "exhaustive conversation" over dinner with ailing North Korean leader Kim and his top aides.

The White House denied a report by North Korea's news agency KCNA that said Clinton had carried a message to North Korea from U.S. President Barack Obama.

"That's not true," White House spokesman Robert Gibbs told reporters in Washington. Obama adviser David Axelrod told MSNBC that Clinton was on a "private humanitarian mission" and that "I don't think it's related to other issues."

The two journalists were arrested on the North Korea-China border in March and accused of illegal entry. A North Korean court sentenced both of them last month to 12 years hard labor for what it called grave crimes.

Arriving on a private jet on a trip to North Korea he had hoped to take before leaving office in January 2001, Clinton was presented with flowers by a girl dressed in traditional costume before he was led to a black limousine and driven away.

The North Korean news agency said Clinton passed on a verbal message from Obama.

"Kim Jong Il expressed thanks for this," KCNA said of the message. "He welcomed Clinton's visit to the DPRK [North Korea] and had an exhaustive conversation with him. There was a wide-ranging exchange of views on the matters of common concern."